The stethoscope is a medical device for auscultation, i.e. listening to internal sounds in the human body. It is most often used to listen to heart and lung sounds, though it is also used to listen to the intestines and to the blood flow in both arteries and veins. Since its invention in 1819, the stethoscope has been used to listen to sounds within the human body as an aid in the diagnosis of certain diseases or health conditions. Prior to the invention of the stethoscope, a doctor listened to sounds from within the body by placing an ear against the patient's chest or elsewhere next to the patient's body.
Conventional stethoscopes include a sound receiving member (or chestpiece) which is configured for placement against the surface of a patient's skin to capture internal body sounds such as those emanating from the heart, lungs, blood vessels or the like. Traditionally, there have been two types of sound receiving members provided with conventional stethoscopes, the bell type and the diaphragm type. The bell type of sound receiving member is typically used to pick up low-pitched sounds while the diaphragm type picks up high-pitched sounds. Doctors may sometimes use a stethoscope having a combination bell/diaphragm sound receiving member. The diaphragm sound receiving member includes a membrane, or diaphragm, that selectively vibrates to sounds (e.g., a heart sound) generated within a certain frequency range from within the body to thereby amplify those sounds. Sound entering the bell type sound receiving member or the diaphragm sound receiving member is transmitted through tubing connected to a headset having a pair of earpieces configured to fit within the ears of the physician, nurse or other trained healthcare professional.
While stethoscopes employing diaphragm sound receiving members have been effective in the amplification of certain sound frequencies in the body, they have not been completely effective in reducing the level of “noise” entering the contact piece of the stethoscope. Sources of unwanted noise include frictional noises, for example. In one aspect, frictional noise arises as a result of friction between the sound receiving member of and the skin or clothing on a patient's body to which the sound receiving member is applied. Other sources of frictional noise can also include the friction between the physician's hands or fingers as he/she grasps the sound receiving member, or the friction between the hands of the physician and the tubing or other portions of the stethoscope.
The more recent development of electronic stethoscopes have utilized designs which incorporate a transducer as a sound receiving member to transform sound waves into an electrical signal. The transducer picks up the incoming sound and transmits it to signal conditioning circuits such as amplifiers or electronic filters which send the conditioned signal to speakers located in the earpieces of the stethoscope. While electronic stethoscopes can greatly amplify body sounds (e.g., the heartbeat), they also amplify the unwanted frictional noise arising as a result of the contact between the transducer (or a surface associated with the transducer) and the skin or clothing of a patient. These unwanted sounds can obscure the sounds of interest. In some cases, unwanted sounds can be amplified to an intensity that can cause discomfort to the user of the stethoscope.
The presence of frictional noise during auscultation can obscure certain sounds completely or at least diminish the ability of the physician to detect clinically significant sounds. Consequently, there is a need to provide a stethoscope or an improvement or modification of a stethoscope that is effective in reducing the level of frictional noise heard by the user.